The present invention relates to an electromagnetic radiation detection matrix comprising thin-film transistors.
It also relates to radiological image intensifiers comprising such a matrix.
Thin-film transistor electromagnetic radiation detection matrices are generally formed from photosensitive elements, photodiodes or photoconductances, formed with thin-film techniques on the same dielectric substrate and disposed at each crossing point of lines and perpendicular columns.
Means for addressing each line of photosensitive elements are formed by an MOS transistor, formed by thin-film technology and associated with each photosensitive element. Each addressing transistor receives periodically at its gate a turn-on pulse applied simultaneously to all the addressing transistors in the same line of photosensitive elements, and is connected to means for transferring to a video amplifier electric signals supplied by each line of elements addressed.
Finally, means for amplifying the electric signal supplied by each photosensitive element are associated with each of these elements and formed in accordance with thin-film technology.
The name of elementary module is given to the assembly formed of a photosensitive element with which are associated addressing and amplification means and different elements such as a resistor or a capacitor.
Such detection matrices comprise a number of intersections between connection lines. These intersections form a considerable limitation as regards the efficiency in manufacturing these devices.
In fact each intersection forms a fragile point in the implantation of such matrices. There may occur interruption of the electric continuity for the connecting part which crosses the step of insulating material intended to separate electrically the lower and upper connections. There may also occur a short-circuit between the upper and lower connections.
Depending on the type of connection and the organization of the lines and columns, these defects may saturate a line and a column or, on the contrary, disable them.
A reduction in the number of intersections between electrodes would then provide a solution for the problems raised; this is what the present invention proposes doing in the case where the photosensitive elements are formed by photoconductances.
The invention allows the number of intersections per elementary module to be reduced by half. It increases in addition the useful detection surface.